The shock poll from the Des Moines Register that dropped like a bomb Saturday evening showing Trump trailing Ted Cruz by ten points in Iowa jolted a race that seemed frozen more or less since the summer. It also opened fascinating new prospects ahead.

For the first time since he entered the race early last summer, Trump has been seen to be losing in something, a possibility he seems to have never imagined, and for which he has never prepared. Predictably, his response was to call the poll bogus, though lucid observers call it the gold standard, and he has boasted of polls that are much less reliable.